2 - (phenylalkylamino)ethanethio-sulfuric acids as antiradiation agents

ABSTRACT

N-SUBSTITUTED 2-AMINOETHANETHIOSULFURIC ACIDS OF THE FORMULA:   R-NH-CH2-CH2-SSO3H   WHEREIN R REPRESENTS ALKYL OR PHENYL ALKYL, ARE EFFECTIVE ANTIRADIATION DRUGS FOR ANIMALS. THE COMPOUNDS ARE USEFUL IN PREVENTION OF CELLULAR DAMAGE FROM RADIATION. THE METHODS OF PREPARATION INCLUDE THE REACTION OF A PRIMARY BROMO HYDROCARBON WITH 2-AMINOETHANETHIOSULFURIC ACID, REACTING A 2 (SEC-ALKYL AMINO) ETHYL BROMIDE HYDROBROMIDE WITH SODIUM THIOSULFATE PENTAHYDRATE, AND REACTING AMMONIUM THIOSULFATE WITH A 1-SUBSTITUTED AZIRIDINE.

United States Patent 3,595,899 2 (PHENYLALKYLAMINO)ETHANETHIO-SUL- FURIC ACIDS AS ANTIRADIATION AGENTS Daniel L. Klayman, Chevy Chase, Md., and William Franklin Gilmore, Oxford, Miss., assignors to the United States of America as represented by the Secretary 0f the Army No Drawing. Continuation-impart of abandoned application Ser. No. 506,291, Nov. 3, 1965. This application June 17, 1968, Ser. No. 737,358

Int. Cl. C07c 141/00 U.S. Cl. 260-453 2 Claims ABSTRACT OF THE DISCLOSURE N-subsituted 2-aminoethanethiosulfuric acids of the formula:

wherein R represents alkyl or phenyl alkyl, are effective antiradiation drugs for animals. The compounds are useful in prevention of cellular damage from radiation. The methods of preparation include the reaction of a primary bromo hydrocarbon with Z-aminoethanethiosulfuric acid, reacting a 2 (sec-alkyl amino) ethyl bromide hydrobromide with sodium thiosulfate pentahydrate, and reacting ammonium thiosulfate with a l-substituted aziridine.

The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to us any royalty thereon.

CROSS REFERENCE TO RELATED APPLICATIONS This is a continuation-in-part of our patent application filed Nov. 3, 1965, Ser. No. 506,291 now abandoned.

BACKGROUND OF THE INVENTION (1) Field of the invention It has been discovered that N-substituted aminoethanethiosulfuric acids of the general formula:

wherein R represents a linear or branched alkyl chain, preferably having from 1 to 18 carbon atoms, or a phenyl alkyl wherein the alkyl chain has from 1 to 6 carbon atoms attached, are effective antiradiation drugs for mammals.

(2) Description of the prior art Destruction of cellular components from radiation exposure has been thought to result either because the radioactive particles cause the direct inactivation of some essential component of the cell by ionization, or indirect inactivation by an intermediate which is produced by radiation and which then reacts with a critical component. See Thomson, Radiation Protection in Mammals, 5, Reinhold Publishing Co. (1962).

It has been found that certain chemicals, introduced into the body prior to exposure, act as protective agents thereby permitting the body to sustain an amount of radiation which would constitute a lethal dosage without the introduction of said chemical compounds.

Laboratory experiments use as a criterion a 30-day ice LD This term is defined as that amount of radiation required to cause the death of all of the exposed subjects within '30 days. For example, to cause the death of 50 percent in 30 days the LD for mice varies from 400 to 700 roentgens (hereinafter referred to as 1'.) depending on the strain. The LD for some strains of guinea pigs is about 200 r. and around 800 r. for rabbits. The 30 day LD for man is estimated at between 400 and 500 r. Exact data depends on many variables such as age, sex, and diet. See Thomson, p. 10. Other meaningful criteria involve a correlation between the dose rate in milligrams per kilogram of body weight and percent survival.

Laboratory procedure in evaluating a chemical as a radiation protective agent usually follows the procedure of injecting a sublethal dose of the chemical dissolved in water into groups of subjects, and then evaluating the new LD for the exposed animals. The activity of a chemical protective agent is evaluated on the basis of the increased LD after injection with the agent, against a control group. For example, Smith et al. in 73 Proc. Sec. Exptl. Biol. Med. 198 (1950) disclosed that 1000 r. given an animal previously treated with 1200 mg./kg. of cysteine will produce the same degree of mortality as 600 r. in an untreated animal (cited in Thomson, p. 56).

It is known that various thiols are effective antiradiation compounds. See Thomson, p. 53. Rosenthal in U.S. Pat. No. 3,284,297, issued Nov. 8, 1966, disclosed that 2-N-methylammoniumethylthiosulfuric acid was an effective antiradiation compound. However, research in the area of thiosulfuric acids was abandoned due to the fact that an enormous dosage of around 300 mg./kg. was necessary with the lower alkyl substituent in order to achieve only a percent survival ratio.

SUMMARY OF THE IbWENTION It has now been discovered that certain higher linear and branched chain alkyl and phenyl alkyl N-substituted 2-aminoethanethiosulfuric acids are particularly effective antiradiation drugs having a high LD, and a high efficiency for a relatively small dosage. These new compounds are also synthesized according to three new processes hereinafter described.

Accordingly, it is an object of this invention to synthesize the N-substituted family of 2-aminoethanethiosulfuric acids.

It is another object to provide N-substituted 2-aminoethanethiosulfuric acids for use as antiradiation drugs.

It is a further object to provide N-substituted Z-aminoethanethiosulfuric acids having low toxicity for mammals, and highly eflicient antiradiation properties in mammals.

These and other objects will be obvious with reference to the following description.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following table lists fifty-one compounds synthesized according to the processes of the invention and compiles the results of tests according to standard laboratory procedures on test groups of rodents. The table compares radiation dosage with drug dosage per kilogram of body weight to achieve percent survival or efliciency. The table also contains toxicity data in terms of an LD,, evaluated over 1 or 2 days. The period of time is short because the rodents normally die within one day. The data was compiled using ordinary laboratory procedures.

Rodent Time drug dose Radiation interval Percent LD50 Compound Formula (mg/kg.) dose (1:) (min.) survival (mg/kg.)

1 Methyl C I-IqN s2 300 800 15 70 350 C4H11NO3S2 300 1,000 30 55 525 cfirr Noasz 225 925 15 30 350 C6H15NO3S2 200 1,000 15 7 300 a. C7H17NO3S2 50 1,000 30 0 200 CsH19NO3S2 75 1, 000 15 0 85 0 111 190 52 75 1,000 30 50 125 CioHaNmSz 15 1,000 30 so 125 CIIHMNOQS'J 15 1,000 30 a7 10 C12H97NO3S2 975 30 00 13 0131129010332 5 1, 000 15 0 8 C I-1311s 05$: 5 1,000 30 0 01511 190189 5 1,000 30 40 n-TetradeeyL 0 11351 10382 5 1, 000 30 10 n-PentadecyL. c 11 N0 s2 1, 000 30 7 n-Hexadecyl GisHmNOssz 40 325 30 0 150 11-Hept2dQOYL. CmHuNOsSZ 100 800 30 0 200 D'OCbildQCYL- CmHnNOsS: 250 800 30 O 400 C5H13N03S2 250 800 30 0 270 011113190382 150 1, 000 15 0 300 CnH15NOaS2 200 825 15 10 250 2,2-dimethylpropyl C7H17NO3S2 200 1, 000 15 0 475 Cyclobutylmethyl- C7I'I15N03S2 100 1, 000 15 0 180 2.115 t CQIIQ1NO3S2 75 1,000 15 0 175 CgI'I19N03S2 50 1, 000 15 0 75 C1uHz3NOaS2 75 1, 000 30 100 138 C10I'I23NO3S2 75 1, 000 0 40 125 cm-.. 10 23N 3 2 75 800 -15 33 140 Cyelooctyl. 0101121190352 100 800 15 33 150 Z-ethyl-l-hexyl- CmH N 0332 120 1, 000 15 53 180 Isononyl-.. C11H25NO3S2 40 1,000 15 47 140 2 110nyl C11 25N aS2 22. 5 825 30 94 50 3-nonyl Ci1HQ5NO5Sz 50 825 15 80 125 4-nonyl CUH'JJNOBS? 800 15 20 200 3,5,0-trin1ethyll1exyl C111I25NO3S2 20 1,000 30 13 100 l cmlln asz 15 1, 000 30 94 25 C12H27N01S2 25 S00 15 C12H27N 03S? 30 1, 000 30 87 yl C1aH27 2Sz 10 825 30 53 20 Cycloundeoylmethyl. CHI'IQQN 038g 38 1, 000 30 7 160 Beuzyl CBI'IL'AN 03s! 150 1, 000 30 0 250 4-n1etl1oxy "101115190152 100 1, 000 15 0 180 Phenethyl. 10U15N 5Sz 50 800 15 0 150 S-phenylprom CuIlnN 03S: 50 1, 000 15 40 125 Z-phenylbutyL. CmHmNOsSz 50 1, 000 30 13 125 4-phenylbutyL. Cl'lI'IlnNOilSz 120 825 30 114 300 5-plienylpentyL OBIIMNOBSZ 70 825 15 83 6pl1enyll1exyl. cuHaaNoas-z 25 1,000 30 27 38 9-acridy1 C15H11N20sS-7 25 825 30 0 50 B-(m-methoxy)-pl1o11ylpropyl CuIImNOiSz 50 825 15 7 150 51 3,3,3-triphenylpropyl 0231125190532 5 1, 000 30 O The following examples, partially disclosed in our arti- 45 EXAMPLE II cle 7, Journal of Med1cinal Chem1stry 823 (1964), 11- Preparation of P y y lustrate three basic methods of synthesizmg the N-subethanethiosulfuric acid stituted aminoethanethiosulfuric acids of this invention.

To a solution of 2.2 l EXAMPLE I 1 g (0 05 mo e of 1,6 d1bromohex 50 ane 1n 100 ml. of tetrahydrofuran malntained under a Preparation of 2-(n-heptylamino)ethanethiosulfuric acid nitrogen atmosphere at around 9 C., with the aid of To 80.0 g. (2.0 moles) of sodium hydroxide dissolved z g i ii g ig gg dropwlseil 8: holur in 2,400 ml. of warm 95 percent ethanol was added with (7030 b m pageant eny It i so u' stirring a hot solution of 314.4 g. 2.0 moles) of 2- E T resutant 501mm was aminoethanethiosulfuric acid in 200 ml. of water. To the 0 a owe to warm up S Owly overmght and to come up to mixture which was heated under reflux was added over room temperature Over 20 hours- Water 9 mL) was a 64mm period 2865 (1.6 moles) f l bl-omoheptane slowly added to destroy the unreacted phenyllithium. The Heating and stirring were continued for about 24 hours. two P F Were Separated and the Organlc layer Was About 1,800 ml. of ethanol was then distilled from the 60 Washed Wlth Water and than dl'led Over anhydrous mixture and replaced with an equal volume of water. clum chloride. The solvent was evaporated under reduced The solution was neutralized with glacial acetic acid and p essu e and the residue was distilled under reduced prescooled overnight causing the crystalline product to sepasure using a spinning band column. The center cut conrate. The product was removed by filtration and recrystalsistin of -p y h xyl r mide, r fractive index, 17 lized several times to remove the contaminant resulting 65 0f 15250-15285, weighing 4.13 g. (34.2 percent) was from dialkylation. The Z-(n-heptylamino)ethanethiosulused in the succeeding step. furic acid weighed 204 g. (50.0 percent); melting point To 2.56 g. (0.064 mole) of sodium hydroxide dissolved 192194 C. in 80 ml. of 95 percent ethanol was added a hot solution Analysis.Calcd. for C H NO S (percent): C, 42.32, of 10.06 g. (0.064 mole) of 2-aminoethanethiosulfuric H, 8.29; N, 5.49; S, 25.11. Found (percent): C, 42.65; H, 70 acid in 8 ml. of water. To the mixture which was heated 8.55; N, 5.68; S, 24.99. under reflux was added slowly 7.76 g. (0.032 mole) of This same procedure may be applied to the preparation 6-phenylhexylbromide. Heating and stirring were conof the N-substituted acid from any primary bromoalkane tinued for 12 hours. About 40 ml. of ethanol was then with from 1 to 18 carbon atoms or phenyl alkane having distilled from the mixture and replaced with an equal a phenyl group attached to 1 to 6 carbon atoms. 75

volume of water. The solution was neutralized with glacial acetic acid and cooled overnight causing the crystalline product to separate. The product was removed by filtration, and recrystallized several times from acetonitrile to give 4.8 g. (47.2 percent) of -2-(6-phenylhexylamino)ethanethiosulfuric acid, melting point 173174 C.

Analysis.-Calcd. for C H NO S (percent): C, 52.96; H, 7.30; N, 4.41; S, 20.20. Found (percent): C, 53.09; H, 7.01; N, 4.30: S, 20.17.

This same procedure may be applied to the preparation of the N-substituted acid from any alpha, omega di bromo alkanes occupying positions from 1, 2 to 1, 12.

EXAMPLE III Preparation of 2-(4-octylamino)ethanethiosulfuric acid A mixture of 134 g. (0.694 mole) of 4-bromooctane, 127 g. (2.08 moles) of Z-aminoethanol and 150 ml. of xylene was stirred and heated under reflux for 22 hours. The mixture was separated and the Z-aminoethanol layer was washed with benzene. The combined benzene-xylene solution was washed with water and dried over anhydrous magnesium sulfate. The solvents were removed using a rotary evaporator and the residue was distilled under reduced pressure through a Vigreaux column. The fraction boiling at 125-127 C., at 14 mm. Hg pressure, n 1.4496, consisted of 2-(4-octylamino)ethanol. Yield: 73.6 g. (61.2 percent).

A solution of 73.1 g. (0.42 mole) of 2-(4-octylamino) ethanol in 220 ml. of 48 percent hydrobromic acid was heated and the water formed was slowly distilled through a Vigreaux column. When 180 ml. of distillate was obtained the hot solution was diluted with water and evaporated to dryness several times to remove the excess hydrobromic acid. The product, 2-(4-octylamino)ethyl bromide hydrobromide, was recrystallized from water and weighed 44.7 g. (33.6 percent); M.P. 99 C.

A mixture of 31.68 g. (0.1 mole) of 2-(4-octylamino) ethyl bromide hydrobromide, 24.82 g. (0.1 mole) of sodium thiosulfate pentahydrate, 100 ml. of water and 30 ml. of ethanol was heated on a steam bath for approximately 0.5 hour. Completion of the reaction was indicated by the failure of sulfur to precipitate from an aliquot of the solution which had been acidified with mineral acid. Cooling the solution and scratching the interior of the flask caused the product to crystallize. The 2-(4-octylamino)ethanethiosulfuric acid was collected by filtration and recrystallized from water to give 18.8 g. (69.8 percent) of the White material; melting point 117.5- 118 C.

Analysis.-Calcd. for C H NO S (percent): C, 44.58; H, 8.60; N, 5.20; S, 23.80. Found (percent): C, 44.68; H, 8.37; N, 5.16; S, 24.07.

The same procedure may be applied to the preparation of the N-substituted acid from any secondary bromo alkane having from 5 to 18 carbon atoms.

EXAMPLE IV Preparation of 2-(4-phenylbutylamino)ethanethiosulfuric acid To a stirred and ice-cooled solution of 300 g. (2.01 moles) of 4-phenylbutylamine, 6.6 ml. of water and 3 ml. of concentrated hydrochloric acid was added dropwise from an acetone Dry-Ice cooled dropping funnel 29.51 g. (0.67 mole) of ethylene oxide over a period of 1.5 hours. The solution was then heated for 0.5 hour on a steam bath and distilled through a Vigreaux column at reduced pressure. The excess 4-phenylbutylamine distilled first and was followed by 2-(4-phenylbutylamino) ethanol at 155-163C. and 1.5 mm. Hg pressure. The weight of the product Was 67.2 g. (51.9 percent).

A solution of 67.2 g. (0.347 mole) of 2-(4-phenylbutylamino) ethanol and 165 ml. of 48 percent hydrobromic acid was heated and the water which formed was distilled as in Example III. The product, 2-(4-phenylbutylamino) ethyl bromide hydrobromide, was recrystallized from wa- 6 ter and weighed 83.5 g. (71.4 percent); melting point ISO-151 C.

A mixture of 57.9 g. (0.172 mole) of 2-(4-phenylbutylamino)ethyl bromide hydrobromide, 42.44 g. (0.171 mole) of sodium thiosulfate pentahydrate, 400* ml. of water and 40 ml. of ethanol was heated on a steam bath for 0.5 hour as in Example III. The product was recrystallized from 50 percent ethanol to give 43. 6 g. (88.1 percent) of 2 (4 phenylbutylamino)ethanethiosulfuric acid, melting point 181-182 C.

Analysis.Calcd. for C H NO S (percent): C, 49.80; H, 6.62; N, 4.84; S, 22.18. Found (percent): C, 49.91; H, 6.69; N, 4.79; S, 22.27.

This procedure may be applied to the preparation of the N-substituted acid from any alkyl or phenyl alkyl amine having from 1 to 18 carbon atoms.

EXAMPLE V Preparation of 2-(5-phenylpentylamin0) ethanethiosulfuric acid A mixture of g. (0.56 mole) of 5-phenylvaleric acid and 34.3 g. (0.56 mole) of 2-aminoethanol was heated gently at first followed by a gradual increase in the application of heat until the temperature was maintained at 160 to 200 C. The water formed in the course of the reaction was distilled through a Vigreaux column and collected in a Dean-Stark tube. When the calculated volume of Water had been obtained (10 ml.) the crude N-(2-hydroxyethyl)5-phenylvaleramide was permitted to cool to room temperature and was dissolved in 200 ml. of tetrahydrofuran.

The tetrahydrofuran solution of N-(2-hydroxyethyl)-5- phenylvaleramide was added over 2.5 hours to an externally ice-cooled and stirred slurry of 22.77 g. (0.6 mole) of lithium aluminum hydride and 500 ml. of tetrahydrofuran. The mixture was then heated under reflux for 11 hours. Water (250 ml.) was cautiously added to the cooled and stirred mixture to destroy the excess lithium aluminum hydride. The aluminum hydroxide which formed was filtered from the mixture and washed with ether. The aqueous phase of the filtrate was separated from the organic phase and was extracted with ether. The ether washings and the tetrahydrofuran solution were combined and dried over anhydrous magnesium sulfate. The solvent was removed and the residue was distilled at reduced pressure to give 51.9 g. (50.1 percent) of Z-(S-phenylpentylamino) ethanol.

2-(5-phenylpentylamino)ethanol (50.4 g., 0.24 mole) and ml. of 48 percent hydrobromic acid were heated and the water which formed was distilled as in Example III. The product, 2-(5-phenylpentylamino)ethyl bromide hydrobromide, was recrystallized from acetonitrile and weighed 58.4 g. (69.3 percent) melting point 157159 C.

A mixture of 58.4 g. (0.17 mole) of 2-(5-phenylpentylamino)ethyl bromide hydrobromide, 42.2 g. (0.17 mole) of sodium thiosulfate pentahydrate, 100 ml. of water and 100 ml. of ethanol was heated on a steam bath for around 0.5 hour as in Example III. The product was recrystallized from 95 percent ethanol to give 34.9 g. (67.6 percent) of 2-(5-phenylpentylamino)ethanethiosulfuric acid, melting point 188189 C.

Analysis.Calcd. for C H NO S (percent) C, 51.45; H, 6.98; N, 4.62; S, 21.13. Found (percent): C, 51.75; H, 6.77; N, 4.67; S, 21.17.

This procedure may be applied to the preparation of the N-substituted acid from any alkyl or phenyl alkyl mono carboxylic acid having from 2 to 18 carbon atoms.

EXAMPLE VI Preparation of methylaminoethanethiosulfuric acid l-methylaziridine (5.71 g., 0.10 mole) was added to a stirred mixture of 18.53 g. (0.125 mole) of ammonium thiosulfate and 250 ml. of methanol. The entire mixture was heated for 4 hours during which time ammonia was evolved. The excess ammonium thiosulfate was removed by filtration and the filtrate was evaporated to dryness. The residue was recrystallized from water-ethanol to give 8.8 g. (51.4 percent) of methylaminoethanethiosulfuric acid, melting point 165 C. The infrared spectrum was identical to that obtained from the product made by another method.

Analysis.-Calcd. for C H NO S (percent): S, 37.45. Found (percent): S, 37.51.

This procedure may be applied to the preparation of the N-substituted acid from l-substituted aziridine having a substituted alkyl group with from 1 to 13 carbon atoms.

We claim:

1. The compound selected from the class consisting of N-substituted aminoethanethiosulfuric acids of the formula:

RNHCH CH SSO H wherein R is a phenyl alkyl wherein the alkyl chain has from 3 to 6 carbon atoms.

2. A compound selected from the class consisting of N-substituted aminoethanethiosulfuric acids of the formula:

RNHCH CH SSO H wherein R is a member selected from the group consisting of 3-phenylpropyl, 4-phenyl-butyl, S-phenyl-pentyl, and 6-phenyl-hexyl.

References Cited UNITED STATES PATENTS 2,245,971 6/1941 Felix et al 260-453UX 3,352,898 11/1967 James. 3,408,381 10/1968 Westland 260-453 8 3,335,054 8/1967 Reynolds et al. 260-455 3,453,309 7/1969 Westland 260-453 3,468,925 9/1969 Brois 260-453 FOREIGN PATENTS 964,239 7/1964 Great Britain.

OTHER REFERENCES Bretschneider: Monatsh. Chem, vol. 81, pp. 372-373 (1950).

Citarel et al.: Preparation of Radioprotective Agents, US. Government Technical Report #AD294344, ASTIA, 1963.

Klayman et al.: Journal of Medicinal Chemistry, vol. 7, No. 6, pp. 823-824 (1964).

Lecher et al.: Journal of Organic Chemistry, vol. 20, p. 475 (1955).

El-Hewehi et al.: Journal of Praktische Chem., vol. 7, pp. 191 and 193 (1958).

Milligan et al.: Rev. of Pure and Applied Chem., vol. 12, pp. 72-74 (June, 1962).

Wagner et al.: Synthetic Organic Chemistry, pp. 181, 567 and 660 (1963).

Klayman et al.: Synthesis of N-Subs. 2-Aminoethane Thiosulfuric Acids, Nov. 9, 1964.

LEWIS GOTTS, Primary Examiner G. HOLLRAH, Assistant Examiner US. Cl. X.R. 

